I’d like to comment on a few points about the technology underlying passkeys.
You mentioned “secure public key infrastructure,” but as I understand it, WebAuthn (the standard behind passkeys) doesn’t use a PKI in the traditional sense, with Certificate Authorities and so on. It instead uses public-key cryptography, where the security relies entirely on your private key being held securely.
The original design, and the one used by hardware keys like YubiKeys, uses a hardware security module (TPM, such as Secure Enclave) to generate a private key that physically cannot leave the chip. When logging in, the website sends a random challenge and one’s browser passes this to the chip, which is then approved by a touch, password or biometrics. The chip then signs the challenge with the private key. A crucial aspect is that the private key is never exposed, making it immune to phishing because the key is bound to the specific domain (e.g. google.com vs go0gle.com) and unstealable by malware.
This brings me to the “dilution” of the standard by the major platform providers. To solve the “lost phone” problem, they’ve created syncable passkeys. This is where the trust model changes. Contrary to a common misconception (stated for example in a footnote to the Six Colors article you cite), the private keys are still generated and protected inside the Secure Enclave. However, a copy of the key material is then synced via (for example) iCloud or Google’s Password Manager.
This has two major consequences:
- The security of your passkey is now tied to the security of your Apple/Google account and the integrity of their cloud encryption. The “unexportable” promise has been compromised for convenience.
- It creates ecosystem lock-in. There is no standard way to sync passkeys from iCloud to a Windows/Android environment. How do you migrate ecosystems if your digital identity is tied to proprietary sync mechanisms?
So, if a black hat gets a copy of your software-vaulted passkeys (e.g., by compromising a password manager’s vault file, NOT by extracting from a Secure Enclave), can they buy 10 motorcycles on your Amazon account? They would still need to “unseal” the vault, which might require your master password or biometric. But the risk of the key material itself being copied now exists, where it didn’t with a hardware-only key.
I agree with the goals of getting rid of passwords, but I’m concerned that the original, open, interoperable vision based on hardware security has been co-opted into a less secure, vendor-locked system. In my view, a standard for secure, cross-platform key migration should have been a prerequisite.